Ralph Nader grew up in a small town in Connecticut talking politics at the dinner table and at his father's diner. "It was the ultimate expression of free speech," he says. "No matter what political view anyone had they never got a stern look from my father because he liked dissent."

Nader says his father would pound the counter with the challenge for his customers to spend more time improving the country.

Nader says his parents' taught him how to listen and to think critically. Those family values led him to become a lawyer and, he says, to fight injustice.

In 1965 Nader wrote a book called Unsafe At Any Speed. In it he argued that the U.S. automobile industry was knowingly building dangerous vehicles. He specifically targeted a General Motors car, the Corvair. He said the Corvair had design flaws that could lead to accidents.

GM attempted to discredit him and investigated his personal life. Nader sued the company and won. His lawsuit attracted national attention and prompted Congress to pass auto safety legislation. Nader used the settlement money to fight for for safer cars, food, homes and workplaces.

He hired young advocates who became known as Nader's Raiders. In the recent documentary An Unreasonable Man, these former "raiders" say Nader instructed them to "bring their conscience to work every day."

Over the years, Nader's work led to laws requiring seat belts and air bags in all passenger cars. It led to the establishment of new government agencies responsible for occupational safety, environmental protection and consumer product safety. And Nader's aggressive campaign against federal secrecy opened the government to wider public scrutiny, with amendments to the 1974 Freedom of Information Act.

Ralph Nader had transformed consumerism into a movement. In the 1970s, 80s and 90s he published dozens of reports and helped create organizations dedicated to addressing the abuses described in those studies.

In 2000, he entered presidential politics as the candidate of the Green Party, a left-of-center political organization that shunned the policies of both the Democrat and Republican parties. He announced his bid for the White House again in 2004 as an independent, saying that his focus would be on the necessities of the American people. He said the two political parties were broken. "They need a wake-up call. They need somebody to hold their feet to the fire inside the electoral arena."

Speaking to a crowd of democratic supporters in 2004, former President Jimmy Carter told Nader to go back to re-examining the rear end of automobiles. "Don't risk costing the Democrats the White House, this time as you did four years ago," Carter said.

President George W. Bush won re-election in the 2004. Many Democrats dubbed Nader a spoiler for his refusal, once again, to get out of the race. Nader rejects that description of his role. "If we all have an equal right to run for political office, then none of us are spoilers or all of us are spoilers of one another."

Nader is uncompromising on this issue. He puts the blame for the Democrats' loss on the American people and on wealthy corporate donors, which, he says, have a stranglehold on the American political system. He says today, presidential hopefuls must raise hundreds of millions of dollars to be competitive.

That money he says does not come from farmers or housekeepers, but from wealthy people and corporations. He says, "We become a government of the Exxons, by the General Motors, for the Duponts. And that's the end of our democratic society."

Nader, now 73, says he hasn't made up his mind whether to make another run for the White House. But one thing is certain: As a self-proclaimed public citizen, he will continue to let the American people know where he stands.